25905721 has 6 divisors (see below), whose sum is σ = 27341322. Its totient is φ = 24541920.

The previous prime is 25905713. The next prime is 25905743. The reversal of 25905721 is 12750952.

It can be written as a sum of positive squares in only one way, i.e., 20793600 + 5112121 = 4560^2 + 2261^2 .

It is not a de Polignac number, because 25905721 - 2³ = 25905713 is a prime.

It is a super-2 number, since 2×25905721² = 1342212761059682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25905701) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35520 + ... + 36241.

It is an arithmetic number, because the mean of its divisors is an integer number (4556887).

Almost surely, 2^25905721 is an apocalyptic number.

It is an amenable number.

25905721 is a deficient number, since it is larger than the sum of its proper divisors (1435601).

25905721 is an equidigital number, since it uses as much as digits as its factorization.

25905721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71799 (or 71780 counting only the distinct ones).

The product of its (nonzero) digits is 6300, while the sum is 31.

The square root of 25905721 is about 5089.7663011184. The cubic root of 25905721 is about 295.8910947365.

The spelling of 25905721 in words is "twenty-five million, nine hundred five thousand, seven hundred twenty-one".